| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| encoding/hex | Package hex implements hexadecimal encoding and decoding. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go.opencensus.io/metric/metricdata | Package metricdata contains the metrics data model. |
| go.opencensus.io/metric/metricexport | Package metricexport contains support for exporting metric data. |
| go.opencensus.io/stats/view | Package view contains support for collecting and exposing aggregates over stats. |
| go.opencensus.io/trace | Package trace contains support for OpenCensus distributed tracing. |
| log | Package log implements a simple logging package. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| regexp | Package regexp implements regular expression search. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |